Number Of Annealing Cycles Research Articles

GaAs-based optoelectronics grown on GaAs/Si virtual substrates with multiple spaced thermal-cycle annealing

This paper describes the growth of a GaAs-based light-emitting diode (LED) on a GaAs/Si virtual substrate by metalorganic chemical vapor deposition. A GaAs/Si virtual substrate (or template) was formed by depositing a 3.5-μm-thick GaAs epilayer on a (100) Si substrate with the employment of multiple spaced thermal-cycle annealing (TCA). The number of annealing cycle was zero to five in this study to examine crystallinity variation of a GaAs/Si template. High-resolution X-ray rocking curve analysis showed that (400) GaAs crystallinity in terms of full width at half maximum (FWHM) improved significantly with the number of the spaced TCA and then reached a minimum at four annealing cycles. There seems to be no significant difference in crystallinity between the GaAs/Si templates with four and five spaced annealing cycles. The GaAs/Si template with four spaced annealing cycles demonstrated not only an excellent (400) FWHM value of 94.6 arcsec but also a reduced dislocation density of 2.4 × 107 cm−2 evaluated from plan-view transmission electron microscopic observation. Electroluminescence spectra of GaAs-based LEDs grown on GaAs/Si templates showed that emission peak intensity increased monotonically with the number of the spaced annealing cycles. Furthermore, the emission peak intensity of a LED grown on the GaAs/Si template with five spaced annealing cycles reached 80% of a reference LED grown on a GaAs substrate, indicating that the presented multiple spaced TCA method may be useful in obtaining superior crystallinity of a GaAs/Si template for the potential application of monolithic integration of optoelectronic devices with Si.